1. Field of the Invention
The present invention relates to an impeller structure, and more particularly to an impeller structure that may be made easily and may have more blades, so that the impeller has a larger blade driving face, thereby increasing the air flow rate driven by the blades.
2. Description of the Related Art
A conventional axial flow type impeller 90 in accordance with the prior art as shown in FIGS. 1 and 2 comprises a hub 91 provided with a central shaft 92 that may be pivoted to rotate. The hub 91 is provided with a plurality of blades 93. When the impeller 90 is rotated, the blades 93 may drive the air to flow. The conventional axial flow type impeller 90 is made of a plastic material. After the impeller ha been formed in the die, it is stripped from the die. Thus, the head and tail ends 93a and 93b of two adjacent blades 93 have to be located at the two sides of the stripping line That is, the head and tail ends 93a and 93b of any two adjacent blades 93 cannot cross the stripping line to overlap each other. The air flow rate driven by the impeller is positively proportional to the area of the blade 93 that drives the air flow. Thus, if the area of the blade 93 is to be increased, the diameter of the hub 91 has to be increased correspondingly. However, after the conventional axial flow type impeller 90 is formed in the die, it is limited by the stripping restriction. Thus, the driving area of the blade 93 cannot be increased to increase the air flow rate driven by the impeller without increasing the diameter of the hub 91.
The primary objective of the present invention is to provide an impeller structure that may increase the blade area for driving the air flow without increasing the diameter of the hub, thereby increasing the air flow rate driven by the impeller. In addition, the impeller structure may be made easily.
In accordance with the present invention, there is provided an impeller structure including a hub body having one end provided with a top plane which is provided with a central shaft. The hub body has a periphery provided with a plurality of blades. The other end of the hub body is provided with a joint portion that may be combined and secured with the extension hub which has a plurality of blades.
Further benefits and advantages of the present invention will become apparent after a careful reading of the detailed description with appropriate reference to the accompanying drawings.